This invention relates to a process for dehydrogenating light paraffins, in particular C.sub.2 -C.sub.5 (ie paraffins containing from 2 to 5 carbon atoms), in a fluidized bed to obtain the corresponding light olefins.
These form the raw material for a wide range of products such as plastics materials, synthetic rubbers, high-octane gasoline, gasoline antiknock additives, detergents etc.
In these processes the limiting factor is often the poor availability of the olefin, such as isobutene in MTBE (methyl tert-butyl ether) production.
The predicted development in the commercial demand for materials such as MTBE suggests that this limiting factor will become increasingly more critical.
The dehydrogenation reaction in question, by which such olefins are produced from widely available raw materials such as natural gas, is assuming an increasing industrial importance as it enables a considerable quantity of light olefins to be made available to the chemical industry.
Although stolchiometrically simple, the dehydrogenation reaction suffers from considerable kinetic and thermodynamic problems. The dehydrogenation reaction is characterised by an increase in the number of moles and a considerable endothermic character. In this respect, in the C.sub.2 -C.sub.10 range the heat requirement of the reaction is about 27-32 kcal/mol.
This is reflected in the free energy change accompanying the reaction, which in the C.sub.2 -C.sub.5 range remains positive to about 500.degree. C.
A characteristic of these processes is therefore the need to operate at high temperature, ie under operating conditions at which parasite reactions are present such as skeleton isomerization, cracking and coke formation.
Consequently one of the main purposes of the catalyst is to suppress these reactions to the advantage of the dehydrogenation. Finally, the inevitable coke accumulation on the catalyst surface leads to its deactivation. Every process has therefore to include periodic catalyst regeneration.